A research proposal on information processing and short-term memory is organized around four major headings: The first group of studies comprises crucial tests of an earlier model of sensory memory in audition, the PAS model of Crowder and Morton. The second group is also an outgrowth of the PAS model; however, the emphasis is not on the correctness of the model but rather on the analysis of differential performance principles for different categories of speech sound. The differential processing of speech sounds is further explored in the third group by means of experiments on the perception, rather than retention, of speech. The last set of proposed experiments deals with broader aspects of short-term memory and is less concerned with audition and speech than the others.